x86/pvh: Really inline memcmp() and memset() to fix unbootable VMs

Even with __builtin the compiler may decide to use the out of line function
instead of the inline implementation.

The existing code is broken with gcc-14/15 but not gcc-12/13 (Ubuntu 25.10)
and vmlinux no longer boots with CONFIG_PVH if CONFIG_KASAN_GENERIC is set.
The instrumented out of line function performs a memory access to a region not
yet initialized by KASAN, as it is still in the PVH kernel entry point.

For testing purposes, if the size argument in cpuid_base_hypervisor() is
reduced from 12 to 8 the compiler decides to use the inline implementation.
In xen_prepare_pvh(), it (still) decides to use the inline implementation
(at least in these compiler versions), but it is not guaranteed to remain.

Switch the builtin to the inline implementation to address this.

  [ bp: Massage commit message. ]

Fixes: 416a33c9afce ("x86/cpu: fix unbootable VMs by inlining memcmp() in hypervisor_cpuid_base()")
Fixes: fbe5a6dfe492 ("xen, pvh: fix unbootable VMs by inlining memset() in xen_prepare_pvh()")
Signed-off-by: Mauricio Faria de Oliveira <mfo@igalia.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://patch.msgid.link/20260921-pvh-kasan-inline-v10-4-08da47943d8e@igalia.com

0 files changed, 0 insertions, 0 deletions